pinging? knocking? clutch? noise? maybe?

[blueapple]

Hello everyone!
ok, you know when some times you take off from a very low rpm in a fairly old car (by mistake, mostly), say 500RPM, sometimes you get this chattering, sputtering, kinda like pinging noise? Well, I'm getting the exact same noise when I accelerate from a low speed cruise, or even a shift, sometimes.
Say I shift up to second gear, RPM drops to about 1500rpm; as I gas-in and ease off the clutch, I hear a very brief moment of that noise. Never had a car that does this before, it does it to 3rd and fourth gear too, probably 5th gear as well, but by that time the wind noise is too loud for me to hear it.

I always though the low RPM noise is from engine under too much load, so it pings. But for some reason, it seems to be associated with the clutch, because it usually happens at the very moment my foot leaves the clutch. ( when shifting )

My engine doesn't ping going up hill. Maybe the knock sensor detects it and regard the timing, don't know.
By the way, I bought this car a couple of months ago, and had the clutch replaced very soon after the purchase. The guy didn't seem to do a very good job changing the clutch though, the pedal kinda vibrates.
Could it be skipping? since it hasn't seat yet? I told him to resurface the flywheel, I hope he did. about 400miles city driving since the clutch job. All toyota parts, includes a re-man pressure plate

Does anyone know what is making that type of noise?
If it's carbon deposite build up causing engine knock, do you think premium gas would reduce the noise a bit?

[Gary_602Z]

If it is carbon build up for $6.00 for a can of Seafoam you can cure it! Do it anyway as it is the cheapest thing to do! Otherwise it is hard for anybody to diagnose over the internet as we (or you) don't know if it is a ping or a knock.

Gary

[blueapple]

See the thing about seafoam.. and some products Chevron makes, I heard that it's not a good idea to leave it in the tank for too long, best is to burn them out in a relatively short integral, do you guys think that's necessary?

[Gary_602Z]

Run it thru the brake booster line!

Gary

[blueapple]

I got a tank of chevron premium gas today, and very soon after, the noise seems to be less ( well, it was undetectible with windows closed anyways, well, honestly, I needed to run next to a wall to hear it ... when I was running regular ) , now it requires much deeper throttle to trigger the noise. Still the same behavior, it only comes on for less than a second, then goes away. Does it sound like knock sensor detects knocking and kicks in?

In the other hand, I can pull the car up hill at around 1500rpm in 4th gear with the car shaking and no noise at all... ( only half a second when the throttle was first depressed )

Since I bought the car not to long ago, I don't know how long has the engine been doing this, do you think any serious damage can be done when this happens? as in: split seconds of knock every now and again? Considering it's a 5sfe with 99K miles.

Thank you!